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Blood Lead Levels Among Children in a Managed-Care Organization -- California, October 1992-March 1993

Despite substantial progress in reducing exposures to lead among children, as recently as 1991, 9% of children in the United States had blood lead levels (BLLs) of greater than or equal to 10 ug/dL (1) -- levels that can adversely affect intelligence and behavior. In 1991, CDC recommended screening all children for lead exposure except those residing in communities in which large numbers or percentages previously had been screened and determined not to have lead poisoning (2). Subsequently, the California Department of Health Services (CDHS) issued a directive to all California health-care providers participating in the Child Health and Disability Prevention Program to routinely screen children for lead poisoning in accordance with the 1991 CDC guidelines (3). This report presents findings of BLL testing during 1992-1993 from a managed-care organization that provides primary-care services to Medicaid beneficiaries in several locations in California (i.e., Los Angeles County, Orange County, San Bernardino County, Riverside County, Sacramento, and Placerville).

From October 1992 through March 1993, BLLs were measured for 2864 consecutive children aged 1-6 years who received Medicaid benefits. Data were not collected about the number of children whose families did not consent to testing nor about those from whom blood could not be collected. Blood submitted by venipuncture was analyzed by a laboratory certified by the CDHS as proficient in blood lead analysis. Families completed a risk questionnaire (2) about exposures to older housing, home renovation or remodeling, adults with jobs or hobbies that involve lead, and industrial sources of lead, and answered a question about whether the child's playmates or siblings were known to have BLLs greater than or equal to 10 ug/dL. Children were categorized as "low risk" if all five questions were answered "no" or "high risk" if one or more questions were answered "yes."

Overall, 2808 (98.0%) children had BLLs less than 10 ug/dL; 46 (1.7%) had BLLs 10-14 ug/dL, and 10 (0.3%) had BLLs greater than or equal to 15 ug/dL (Table_1 and Table_2). The percentage of children with BLLs greater than or equal to 10 ug/dL was similar across age groups Table_1. Although BLLs varied by clinic site Table_2, no site had a prevalence of elevated BLLs exceeding 4.6%.

The risk questionnaire had a sensitivity of 46%, specificity of 74%, and predictive values positive and negative of 3.4% and 98.6%, respectively. The prevalence of increased BLLs was greater among children identified as high risk (3.4%) than among other children (1.4%, prevalence ratio: 2.4; 95% confidence interval=1.4%-4.1%).

Based on the CDHS reimbursement rate of $22.45 per test, the cost of screening tests per case identified was $1148 to identify a child with a BLL greater than or equal to 10 ug/dL and $9185 to identify a child with a BLL greater than or equal to 20 ug/dL.

Reported by: CD Molina, MD, JM Molina, MD, Molina Medical Centers, Long Beach, California. Lead Poisoning Prevention Br, Div of Environmental Health and Hazard Evaluation, National Center for Environmental Health, CDC.

Editorial Note

Editorial Note: From 1991 through 1993, the number of California children identified with BLLs of at least 25 ug/dL increased from approximately 40 per year to approximately 500 per year (3). Universal screening also has substantially increased the number of lead-exposed children requiring individual management identified in some populations outside California (4).

The burden of lead exposure varies among different U.S. communities and population subgroups. For example, prevalences of elevated BLLs have ranged from 37% among black children who reside in central cities to 5% among non-Hispanic white children who do not live in central cities (1). The prevalences of elevated BLLs in smaller jurisdictions or nonrepresentative clinic-based populations also varies widely, with lead-exposure prevalences ranging from less than 1% (5) to greater than 50% (6). Purposes of this study were to estimate lead-exposure prevalence in the population served by the managed-care organization, assess the performance of a questionnaire in identifying higher risk children, and help assess the usefulness of a universal screening policy in this population.

The finding that prevalences of elevated BLLs were low among Medicaid recipients attending clinics at the managed-care organization was unexpected because previous population-based surveys in Compton and Sacramento had documented substantially higher prevalences of lead exposure (7). However, because the likelihood of lead exposure is greater in the summer and this assessment encompassed winter months (8), seasonal patterns may have accounted for some of the difference. The difference also may have reflected variations in the study design between this (clinic-based) and previous (population-based) assessments (9) and previously documented wide variations in prevalences of elevated BLLs among even apparently homogenous groups (10). Because characteristics of children receiving care at the managed-care organization probably differ from those of other groups of children in California, the findings in this report cannot be generalized.

In this population, a standard risk questionnaire was of limited use in identifying children at higher risk for lead exposure: the prevalence of elevated BLLs was 3.4% in "high risk" children compared with 1.4% in lower risk children. Although this difference was statistically significant, the clinical utility of this finding is limited as a means for targeting blood lead testing. The usefulness of questionnaires to target BLL screening might be increased by adding locally important risk factors to such questionnaires (10). Questionnaires also may be useful in some settings to target education about potentially remediable risk factors for lead exposure regardless of children's current BLLs.

The primary strategy for preventing lead poisoning is to reduce lead sources in the environment before children are exposed. However, because large environmental reservoirs of lead persist, especially in older housing, BLL screening and follow-up of children with elevated BLLs continues to be an important method for controlling lead exposure among children.

The role of universal screening in relatively low-prevalence communities and practices has nonetheless been questioned (6). The purpose of screening is to identify children who require individual follow-up and medical or environmental management (i.e., children whose BLLs are persistently at least 15 ug/dL). In populations such as those served by the managed-care organization, in which small numbers of children who require individual management are identified by universal screening, alternative approaches to the prevention of childhood lead poisoning may include a combination of environmental controls, education, and more selective screening.

References

  1. Brody DJ, Pirkle JL, Kramer RA, et al. Blood lead levels in the U.S. population: phase 1 of the Third National Health and Nutrition Examination Survey (NHANES III, 1988 to 1991). JAMA 1994;272:277-83.

  2. CDC. Preventing lead poisoning in young children: a statement by the Centers for Disease Control. Atlanta: US Department of Health and Human Services, Public Health Service, 1991.

  3. California Department of Health Services. Childhood lead poisoning in California: an update. In: California Morbidity. Berkeley, California: California Department of Health Services, June 1994:21-2.

  4. Schlender TL, Fritz CJ, Murphy A, Shepeard S. Feasibility and effectiveness of screening for childhood lead poisoning in private medical practice. Archives of Pediatrics and Adolescent Medicine 1994;148:761-4.

  5. Robin LF, Beller M, Middaugh JP. Childhood lead screening in Alaska, results of survey of blood lead levels among Medicaid-eligible children. Anchorage, Alaska: Alaska Department of Health Services, October 1994.

  6. Wiley JF, Bell LM, Rosenblum LS, Nussbaum J, Tobin R, Henretig FM. Lead poisoning: low rates of screening and high prevalences among children seen in inner-city emergency departments. J Pediatr 1995;126:392-5.

  7. CDC. Blood lead levels among children in high-risk areas -- California, 1987-1990. MMWR 1992;41:291-4.

  8. Baghurst PA, Tong Shi-Lu, McMichael AJ, Robertson EF, Wigg NR, Vimpani GV. Determinants of blood lead concentrations to age 5 years in a birth cohort study of children living in the lead smelting city of Port Pirie and surrounding areas. Archives of Environmental Health 1992;47:203-10.

  9. Daniel K, Sedlis MH, Polk L, Dowuona-Hammond S, McCants B, Matte T. Childhood lead poisoning -- New York City, 1988. MMWR 1990;39(no. SS-4).

  10. Rooney Bl, Hayes EB, Allen BK, Strutt PJ. Development of a screening tool for prediction of children at risk for lead exposure in a midwestern clinical setting. Pediatrics 1994;93:183-7.



Table_1
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TABLE 1. Blood lead levels (BLLs) among children who were Medicaid beneficiaries and received care from a managed-care
organization, * by age--California, October 1992-March 1993
========================================================================================================================

                                                      Children with elevated BLLs
             Children with            ----------------------------------------------------------------------------------
           ---------------------
Age          BLLs <10 ug/dL             10-14        15-19        20-24                              Total
(yrs)      No.           (%)            ug/dL        ug/dL        ug/dL          >45 ug/dL        No.        (%)
------------------------------------------------------------------------------------------------------------------------
  1        719          (97.8)            13           2            1                0            16        (2.2)
  2        587          (98.3)             9           0            1                0            10        (1.7)
  3        450          (98.7)             4           1            1                0             6        (1.3)
  4        511          (98.5)             5           0            3                0             8        (1.5)
  5        350          (96.7)            11           0            1                0            12        (3.3)
  6        191          (97.9)             4           0            0                0             4        (2.1)

Total     2808          (98.0)            46           3            7                0            56        (2.0)
------------------------------------------------------------------------------------------------------------------------
* Data from sites located in Los Angeles County, Orange County, San Bernadino County,
  Riverside County, and Placerville.
========================================================================================================================

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Table_2
Note: To print large tables and graphs users may have to change their printer settings to landscape and use a small font size.

Table 2. Blood lead levels (BLLs) among children who were Medicaid beneficiaries and received care from a managed-care
organization, by clinic site--California, October 1992-March 1993
=========================================================================================================================

                                       <10 ug/dL           10-14 ug/dL             15-19 ug/dL         20-44 ug/dL
                                     -----------------   ------------------     -------------------   -------------------
Clinic site                           No.       (%)        No.       (%)         No.       (%)         No.       (%)
-------------------------------------------------------------------------------------------------------------------------
Los Angeles County
 Wilmington/Compton                   419     ( 95.4)      17        (3.9)         1       (0.2)        2        (0.5)
 Whittier/El Monte                    323     ( 97.3)       7        (2.1)         0                    2        (0.6)
 Pomona                               475     ( 99.0)       5        (1.0)         0                    0
 Lancaster/Palmdale                   578     ( 99.8)       0                      0                    1        (0.2)
Orange County                         350     ( 97.8)       5        (1.4)         1       (0.3)        2        (0.6)
San Bernardino County                 342     ( 98.3)       5        (1.4)         1       (0.3)        0
Riverside County                      164     ( 97.6)       4        (2.4)         0                    0
Sacramento                            144     ( 98.0)       3        (2.0)         0                    0
Placerville                            13     (100.0)       0                      0

Total                                2808    ( 98.0)       46        (1.7)         3       (0.1)        7        (0.2)
=========================================================================================================================

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